At present, weighted average methods are usually used in coordinate calculation of a touch panel. Such a calculation technique has already been able to meet accuracy requirements in various applications in the touch panel industry. However, when a touch position is close to edges of a touch panel, the conventional calculation methods might cause errors in that this calculation method simply justifies the actual touch position (coordinate) with easy calculation, such that false information is processed and inaccurate response is activated.
FIG. 5 illustratively shows an example of a conventional touch panel calculating method used in a situation where a touch of a user is detected. Taking a sensor array of six rows and eight columns as an example, P11, P12 and P13 respectively represent three touch points, a center of a cross line in each point represents an actual position of each touch, and a range surrounded by a solid-line box represents a touch sensing range.
According to the well-known coordinate calculating methods, taking x coordinates as an example, the x coordinates of the three points P11, P12 and P13 are calculated as follows:
            x      ⁢                          ⁢      coordinate      ⁢                          ⁢      of      ⁢                          ⁢      P      ⁢                          ⁢      11      ⁢                          ⁢              (                  P          ⁢                                          ⁢          11          ⁢                                          ⁢          involves          ⁢                                          ⁢          an          ⁢                                          ⁢          edge          ⁢                                          ⁢          touch          ⁢                                          ⁢          point                )              =                                                      7              ·              0.25                        +            8.1                                0.25            +            1                          -        0.5            =      7.3        ;actually P11 (involving an edge point) has an x coordinate of 7.75, where 7 and 8 are respectively system generated coordinates.
            x      ⁢                          ⁢      coordinate      ⁢                          ⁢      of      ⁢                          ⁢      P      ⁢                          ⁢      12      ⁢                          ⁢              (                  P          ⁢                                          ⁢          12          ⁢                                          ⁢          involves          ⁢                                          ⁢          no          ⁢                                          ⁢          edge          ⁢                                          ⁢          point                )              =                                                      4              ·              0.75                        +                          5              ·              1                        +                          6              ·              0.25                                            0.75            +            1            +            0.25                          -        0.5            =      4.25        ;and an actual x coordinate for P12 is 4.25, where 4, 5 and 6 are respectively system generated coordinates.
            x      ⁢                          ⁢      coordinate      ⁢                          ⁢      of      ⁢                          ⁢      P      ⁢                          ⁢      13      ⁢                          ⁢              (                  P          ⁢                                          ⁢          13          ⁢                                          ⁢          involves          ⁢                                          ⁢          edge          ⁢                                          ⁢          point                )              =                                        1            ·            1                    1                -        0.5            =      0.5        ,where 1 represents system generated coordinate; and actually P13 has an x coordinate of 0.
It is seen from the above calculation that for a touch involving no edge(s), i.e. P12, the difference between the x coordinate calculated by the conventional calculation method and the actual x coordinate is relatively small, while for edge touch points, i.e. P11 and P13, the difference between the x coordinate calculated by the conventional calculation method and the actual x coordinate is relatively big.
When a coordinate of a touch point is calculated using the conventional weighted average methods, touch signals of at least three sensing lines are needed so as to determine the coordinate. However, for a touch point located at the edge of the touch panel, only two sensing lines caused by the user's touch may be detected. If the coordinate is calculated using the touch signals of only two sensing lines (described in the background of the present disclosure), erroneous information indicating where the touch point is actually located may be presented.
Methods for calculating y coordinates in conventional technologies are similar to the methods for calculating x coordinates. Likewise, for a touch point involving edge(s), the difference between y coordinates calculated by the conventional calculation method and the actual y coordinate is relatively big.